Does square 256 represent the positive square root of 256

Normally we use wats called the principal squar root or the positive squar root more oftern then the negative root

techniclly =-16 and +16
so the answer is no

It represents both of them, until it appears in a problem or exercise where there is some reason to discard one or the other.

These are the multiples of 15 but what you are probably asking or what are the factors of 15